Admission Routes and Demographics as Predictors of Academic Performance in Medical Students: A Retrospective Cohort of Grade Point Averages (GPAs) and Comprehensive Exam Scores.

Background: Understanding factors associated with medical school academic performance can inform selection and student support. Traditional measures such as high school grades and standardized test scores are incomplete. Emerging data emphasize the importance of age, gender, entrance route, and exam history on academic outcomes. This study explored associations of age, gender, admission route, nationality, and CBSE attempt number with cumulative basic sciences overall grade point average (GPA) and Comprehensive Basic Sciences Examination (CBSE) scores at Tehran University of Medical Sciences, providing insights for optimizing selection strategies and educational interventions. Methods: Academic records of medical students from 2019 to 2022 were retrospectively collected. Data from the first 5 semesters (2.5 years) of course grades, cumulative GPAs, and CBSE scores were included in the analysis. We conducted univariate and multivariate analyses to examine associations and predictors. Results: A total of 1727 individual records were analyzed. Repeated attempts at the CBSE were associated with progressively lower GPA (P<0.001) and CBSE scores (P<0.001). The admission route had a significant impact on performance (P<0.001), with highly competitive exam entrants achieving the highest mean GPA and CBSE scores, while non-Iranian students had the lowest. Iranian students outperformed their non-Iranian counterparts in both GPA and CBSE (both P<0.001). Male students achieved slightly higher CBSE scores than females (P=0.011), although there was no gender difference in GPA. GPA exhibited modest variation across entry semesters (P=0.003), while CBSE scores remained consistent. The multivariable analyses revealed that admission route and entry year were the leading independent and consistent predictors of academic performance. Conclusion: Repeated CBSE attempts, admission route, and nationality were associated with academic performance. Highly competitive entrants achieved the highest, while non-Iranian students and repeat examinees showed comparatively lower outcomes. These findings highlight the need for targeted academic support and early intervention strategies to promote equitable achievement among diverse medical student groups.